Stacked Cake

Im making a two tiered stacked cake. The bottom will be chocolate cake and the top tier will be a polystyrene block. I was told before that when making a stacked cake the height of each tier should get shorter as the cakes get smaller, is this true?

Never heard that one before! Sometimes the tiers can be different heights just to give it some artistic style but to specifically make the tiers shorter as the cakes get smaller...I think the cake would end up looking squatty. JMHO